Acne is a chronic inflammation of hair follicles sebaceous glands, and it is a common inflammatory skin disease in adolescence, frequently occurring in the cheeks, forehead, and nasolabial fold, followed by the chest, back and shoulders. Its incidence is mainly associated with the sex hormone level, large sebaceous secretion, P. acnes proliferation, keratinization of hair follicle sebaceous duct and inflammation. During adolescence, the skin lipid components have changed, and the androgen increases, resulting in hyperkeratosis of sebaceous follicle duct, mixture of epithelial cells and sebum in the hair follicle wall to form embolism in the hair follicles and acnes. When affected with propionibacteria and bacterial infection, it will cause inflammation and produce abscess, making patients very painful.
When the body is affected by various carcinogenic factors, the growth of a cell in local tissue may not be normally regulated at the gene level, which results in clonal abnormal proliferation and forms a tumor. Tumors are divided into two types: benign and malignant tumors according to their harms to human body and growth characteristics. Malignant tumors grow rapidly and often infiltrate the adjacent tissues when growing, without envelop on the surface, and accompanied by systemic metastasis. At present, the incidence of malignant tumors has been increasing year by year which is a major reason of deaths in various diseases; therefore, the prevention and treatment are very important.
Antimicrobial peptide is a kind of bioactive low molecular polypeptide induced in vivo. Its molecular weight is about 1000˜7000. The antimicrobial peptide consists of 10˜60 amino acid residues. Antimicrobial peptide is an efficient and broad-spectrum antimicrobial peptide molecules quickly produced by the body when an organism is invaded by microorganisms, to involve in the body's immune response. Antimicrobial peptides widely exist as effective defensive molecules in the body. At present, thousands of antimicrobial peptides have been identified from microorganisms, plants, insects, arthropods, amphibians, mammals and even humans. The antimicrobial mechanism of antimicrobial peptides is complex, but most of theories consider that its mechanism involves the cationic and hydrophobic properties of antimicrobial peptides and the actions with the negatively charged microbial cell membrane; and when antimicrobial peptides contact with bacterial cell membranes, it will cause changes in membrane permeability, or form a transmembrane hole on the bacterial cell membrane, finally resulting in the leakage of bacterial contents and death. As a result, antimicrobial peptides are much stronger in killing bacteria than traditional antibiotics, and unlike antibiotics, which inhibit bacterial growth at low concentrations, antimicrobial peptides are almost fatal to bacteria. The results show that compared with traditional antibiotics, antimicrobial peptides do not readily induce the antibacterial spectra by the drug-resistant strains. It can produce effects on bacteria, fungi, viruses, protozoa and cancer cells. Three families of antimicrobial peptides have been found in poultry, including cathelicidin, liver-expressed antimicrobial peptide (LEAP), and β-defensin. These antimicrobial peptides are crucial for poultry's resistance to bacterial and viral diseases. Mutations or deletions of these genes will have a significant impact on the ability of poultry to resist microbial infection. In addition to broad-pectrum antibacterial activity, these antimicrobial peptides are highly effective against fungi, viruses, protozos and/or tumors, for example, Bat5 and Mc7 can kill Leptospira, Candida albicans, Cryptococcus and membrane viruses and parasites; some antimicrobial peptides have obvious killing effect on Herpes virus, influenza virus, HIV and enveloped virus. In addition, some antimicrobial peptides also have a variety of other regulatory functions, for example, Cathelicidin has the functions of prompting wound healing, tissue damage repair, chemotaxis, pro-angiogenesis and anti-parasites, etc., having has important biological activity in regulating animal body immunity.